%0 Journal Article
%T Modulation of neuronal dynamics by sustained and activity-dependent continuous-wave near-infrared laser stimulation.
%A Garrido-Peña A
%A Sanchez-Martin P
%A Reyes-Sanchez M
%A Levi R
%A Rodriguez FB
%A Castilla J
%A Tornero J
%A Varona P
%J Neurophotonics
%V 11
%N 2
%D 2024 Apr
%M 38764942
%F 4.212
%R 10.1117/1.NPh.11.2.024308
%X <B>UNASSIGNED: </B>Near-infrared laser illumination is a non-invasive alternative/complement to classical stimulation methods in neuroscience but the mechanisms underlying its action on neuronal dynamics remain unclear. Most studies deal with high-frequency pulsed protocols and stationary characterizations disregarding the dynamic modulatory effect of sustained and activity-dependent stimulation. The understanding of such modulation and its widespread dissemination can help to develop specific interventions for research applications and treatments for neural disorders.<BR><B>UNASSIGNED: </B>We quantified the effect of continuous-wave near-infrared (CW-NIR) laser illumination on single neuron dynamics using sustained stimulation and an open-source activity-dependent protocol to identify the biophysical mechanisms underlying this modulation and its time course.<BR><B>UNASSIGNED: </B>We characterized the effect by simultaneously performing long intracellular recordings of membrane potential while delivering sustained and closed-loop CW-NIR laser stimulation. We used waveform metrics and conductance-based models to assess the role of specific biophysical candidates on the modulation.<BR><B>UNASSIGNED: </B>We show that CW-NIR sustained illumination asymmetrically accelerates action potential dynamics and the spiking rate on single neurons, while closed-loop stimulation unveils its action at different phases of the neuron dynamics. Our model study points out the action of CW-NIR on specific ionic-channels and the key role of temperature on channel properties to explain the modulatory effect.<BR><B>UNASSIGNED: </B>Both sustained and activity-dependent CW-NIR stimulation effectively modulate neuronal dynamics by a combination of biophysical mechanisms. Our open-source protocols can help to disseminate this non-invasive optical stimulation in novel research and clinical applications.